Referring to FIG. 1, U.S. Patent Application Publication No. 2013/0233384 discloses a light collector that includes a light guide layer 114 and a light insertion layer 112 disposed over the light guide layer 114. The light insertion layer 112 includes a plurality of pie-shaped annular bodies 172 made from a material, such as silicone. Each of the pie-shaped annular bodies 172 has a planar edge surface 170, a parabolic surface 160, and a planar interface 159 that is annular in shape and that is deformed so as to be brought into contact with a contact surface 130 of the light guide layer 114. The planar interface 159 of each of the pie-shaped annular bodies 172 forms an optical exit of the light insertion layer 112, such that the light insertion layer 112 is formed with an array of the optical exits. The optical exits cooperate with the contact surface 130 of the light guide layer 114 to form an array of annular optical apertures. In operation, light 122 entering each of the pie-shaped annular bodies 172 is reflected by the parabolic surface 160 via total internal reflection (TIR) toward the optical exit and pass through the optical aperture into the light guide layer 114. The planar interface 159 of each of the pie-shaped annular bodies 172 is small in area relative to the size of the pie-shaped annular body 172, thereby reducing the amount of light 122 that will escape the light guide layer 114 through the optical aperture and not thus be available for harvesting.
Referring to FIG. 2, the aforesaid conventional light collector is disadvantageous in that since the planar edge surface 170 is straight and is transverse to the light guide layer 114, light 122 reflected from the parabolic surface 160 may travel through the planar edge surface 170, which results in incorrect focus and a decrease in converging the light 122, which, in turn, results in a decrease in light coupling efficiency. In addition, the shape of the pie-shaped annular bodies 172 renders the light collector to have a low fill factor in area, which results in a decrease in the light collecting efficiency for the light collector.